苏里格气田东区下奥陶统马五_5厚层白云岩储层成因

苏里格气田东区下奥陶统马五_5白云岩储层具有单井厚度大、横向尖灭快等特征,显著区别于邻区靖边气田的马五_(1–4)亚段白云岩单层薄且连片分布特征。本区储层岩性主要为细中晶白云岩和细粉晶白云岩,是蒸发泵白云化、回流渗透白云化和埋藏白云化等三种模式共同作用的结果。孔隙类型主要为晶间孔和晶间溶孔。通过岩石学、地球化学、成岩作用等方面研究,探究得到本区白云岩储层成因:颗粒滩沉积微相是形成有利储层的重要条件,埋藏白云岩化作用是先决条件,埋藏期溶解作用是储层形成的关键因素。

Genesis of thick dolomite in the lower Ordovician Ma 5_5 in eastern area of the Sulige gas field

Dolomite reservoirs in M5_5 of lower Ordovician in eastern area of the Sulige gas field is characterized by big thickness of single well,quick pinching out in horizontal direction,which is distinctively different from the characteristics of dolomites reservoir in M5_(1-4) with thinner individual layer and good horizontal continuance in the Jingbian gas field.The reservoir lithology of this area is mainly of fine medium dolomite and fine powder crystal dolomite,which is the result of the combination of evaporation pump dolomization,reflux permeation dolomitization and deep-burial dolomitization.The dolomite types are mainly of fine or medium dolomites and fine or silty crystal dolomite,the pore types are mainly intercrystal pore and intercrystal dissolved pore.Through the research of petrology,geochemistry and diagenesis,the genesis of dolomite reservoir in this area was studied.The grain bank deposition is an important condition for the formation of favorable reservoirs,the burial dolomitization is a precondition,and the burial phase dissolution is a key factor for reservoir formation.